Image sensing device

Abstract

An image sensing device includes: a light source, a recording member on which an image is formed and conveyed in one direction, illumination system for causing a light beam emitted from the light source to obliquely illuminate the recording member and, imaging system for condensing specularly reflected light from the image on the recording member and causing the reflected light to travel to a surface of a photodetector, so that the image sensing device obtains positional information of the image on the recording member on the basis of a signal obtained by the photodetector. When the amount of displacement of the recording member in a vertical direction during conveyance of the recording member is d, an angle between the optical axis of the imaging system and a normal to the recording member is θ (degrees), and resolution of the image formed on the recording member is R (dpi), the components are set so that d· tan θ<(25.4/ R )×1000 is satisfied.

1. An image sensing device comprising:
 light source means;  
 a recording member on which an image is formed, said recording member being conveyed in one direction;  
 illumination means for causing a light beam emitted from said light source means to obliquely illuminate said recording member; and  
 imaging means for condensing specularly reflected light from the image on said recording member and causing the reflected light to travel to a surface of light receiving means, said image sensing device obtaining positional information of the image on said recording member on the basis of a signal obtained by said light receiving means,  
 wherein when the amount of displacement of the recording member in a vertical direction during conveyance of said recording member is d, an angle between the optical axis of said imaging means and a normal to said recording member is θ (degrees), and resolution of the image formed on said recording member is R (dpi), the components are set so that 
     d· tan θ<(25.4 /R )×1000 is satisfied.  
 
 
   
   
     2. A device according to  claim 1 , wherein the angle θ (degrees) satisfies
   5°<θ<35°.  
 
   
   
     3. A device according to  claim 1 , wherein said light source means comprises an LED light source, and said illumination means includes an illumination lens for condensing a light beam from said LED light source and causing the light beam to travel to said recording member. 
   
   
     4. A device according to  claim 1 , wherein said imaging means includes an imaging lens for forming, on a surface of said light receiving means, an image on said recording member. 
   
   
     5. A device according to  claim 1 , further comprising an imaging lens for forming, the image on the recording member onto said light receiving means, wherein when imaging magnification of said imaging lens is assumed to be β,
   0.75<|β|<1.25 is satisfied.  
 
   
   
     6. A device according to  claim 1 , wherein the angle θ (degrees) satisfies
   25°<θ<35°.  
 
   
   
     7. An image forming apparatus including an image sensing device according to  claim 1 , wherein said image forming apparatus includes a plurality of image bearing members and forms a color image by using said image sensing device. 
   
   
     8. An image sensing device comprising:
 light source means;  
 illumination means for irradiating, with a light beam from said light source means, a recording member on which an image is formed; and  
 imaging means for forming, onto a surface of a light receiving means, the image on said recording member, said image sensing device detecting the image on the recording member on the basis of a signal obtained by said light receiving means,  
 wherein when said recording member has a specular reflection surface, a stop is provided to a position to be substantially optically conjugate with the light emitting point of said light source means.  
 
   
   
     9. A device according to  claim 8 , wherein when the imaging magnification at which the light emitting point of said light source is imaged at the conjugate position is assumed to be β,
   1<|β|<7 is satisfied.  
 
   
   
     10. A device according to  claim 8 , wherein the aperture of the stop has a size substantially equal to or smaller than the size of the image of the light emitting point of said light source means. 
   
   
     11. A device according  claim 8 , wherein the stop is disposed between said imaging means and said light receiving means. 
   
   
     12. A device according to  claim 8 , wherein said light receiving means detects the image formed on said recording member to obtain positional information of the image. 
   
   
     13. A device according to  claim 8 , wherein said light receiving means detects density of the image formed on said recording member. 
   
   
     14. An image forming apparatus including an image sensing device according to  claim 8 , wherein said image forming apparatus forms a color image by using said image sensing device, and
 wherein said image forming apparatus includes a plurality of image bearing members.  
 
   
   
     15. A device according to  claim 8 , wherein said illumination means includes an irradiation lens, wherein said imaging means includes an imaging lens, and wherein at least one of the surface of said irradiation lens and said imaging lens on said recording member side is flat. 
   
   
     16. A device according to  claim 15 , wherein at least one of said irradiation lens and said imaging lens has at least one rotationally symmetrical aspherical surface. 
   
   
     17. A device according to  claim 15 , wherein at least one of said irradiation lens and said imaging lens has at least one anamorphic surface. 
   
   
     18. A device according to  claim 15 , wherein at least one surface of said irradiation lens and said imaging lens is inclined relative to a surface normal to said recording member. 
   
   
     19. A device according to  claim 15 , wherein said irradiation lens and said imaging lens are formed integrally with each other and are made of a same material. 
   
   
     20. A device according to  claim 15 , wherein an optical axis of said irradiation lens and an optical axis of said imaging lens have equal angles formed in opposite directions from a surface normal to said recording member. 
   
   
     21. A device according to  claim 15 , wherein said light source means is provided with a moving mechanism capable of displacing to an arbitrary position. 
   
   
     22. A device according to  claim 15 , wherein said light receiving means is provided with a moving mechanism capable of displacing to an arbitrary position. 
   
   
     23. A device according to  claim 15 , wherein said imaging means has a stop, and a light emitting surface of said light receiving means and the stop are made substantially conjugate with each other when a surface of said recording member is a specular reflection surface. 
   
   
     24. A device according to  claim 15 , wherein said light receiving means detects the image formed on said recording member to obtain positional information of the image. 
   
   
     25. A device according to  claim 15 , wherein said light receiving means detects density of the image formed on said recording member.